The Doctor was called in because the patient was feeling poorly and was unable to go to work. On closer examination a milky, gassy, dark brown substance was found to be the culprit. Why, do you ask, is your vacuum furnace not producing acceptable parts? Perhaps part of the answer lies in the fact that your vacuum-pump oil is in need of gas ballasting. Let’s learn more.
Gas ballasting is essential for oil-sealed pumps such as rotary-vane (i.e., mechanical) pumps, but it is often poorly understood or neglected as part of the daily maintenance routine on a vacuum furnace. As a matter of good practice, it should be done for about 20-30 minutes each day and is normally performed before processing parts (not once the furnace is running a load!).